CONN 

S 

43 

.E22 

no.135 


Q  £,  s  library-  Cop.  2. 

CONNECTICUT 

AGRICULTURAL  EXPERIMENT  STATION 

NEW     HAVEN,    CONN. 


BULLETIN    135,  DECEMBER,  1901. 


ENTOMOLOGICAL    SERIES,    No.    5. 

The  San  Jose  Scale-Insect:  Its  Appearance 
and  Spread  in  Connecticut. 


CONTENTS. 

Page 

Officers  and  Staff  of  Station - 2 

The  San  Jose  Scale-Insect :  Its  appearance  and  spread  in  Connecticut.  3 

Introduction  into  the  Eastern  States 3 

Discovery  and  Distribution  in  Connecticut 4 

Nursery  Inspection  in  Connecticut 5 

Legislation 5 

Life  History  of  the  San  Jose  Scale 6 

General  appearance  of  the  Insect 6 

Food  Plants 8 

How  the  Scale  Spreads  from  Tree  to  Tree 9 

Effect  upon  Trees 10 

Remedies 10 

Summary 13 


CONNECTICUT  AGRICULTURAL  EXPERIMENT  STATION, 

OFFICERS    J^l&lD    STAFF. 


STATE   BOARD    OF   CONTROL. 

Ex  officio. 
His  Excellency  George  P.  McLean,  President. 

Appointed  by  Connecticut  State  Agricultural  Society  : 
B.  W.  Collins,  Meriden. 

Appointed  by  Board  of  Trustees  of  Wesley  an  University  : 
Prof.  W.  O.  Atwater,  Middletown. 

Appointed  by  Governor  and  Senate  : 
Edwin  Hoyt,  New  Canaan. 
James  H.  Webb,  Hamden. 

Appointed  by  Board  of  Agriculture  : 
T.  S.  Gold,  West  Cornwall,   Vice-President. 

Appointed  by  Governing  Board  of  Sheffield  Scientific  School. 
W.  H.  Brewer,  New  Haven,  Secretary  and  Treasurer. 

Ex  officio. 
E.  H.  Jenkins,  New  Haven,  Director. 


STATION    STAFF. 

Chemists. 

E.  H.  Jenkins,  Ph.D.,  Director.  T.  B.  Osborne,  Ph.D. 

A.  L.  Winton,  Ph.B.  A.  W.  Ogden,  Ph.B. 

I.  F.  Harris,  B.S.  M.  Silverman,  Ph.B. 

Botanist. 
William  C.  Sturgis,  Ph.D. 

Entomologist. 
W.  E.  Britton,  B.S. 

In  charge  of  Forestry  Work. 
Walter  Mulford,  B.S.F. 

Grass  Gardener. 
James  B.  Olcott,  South  Manchester. 

Stenographers  and  Clerks. 

Miss  V.  E.  Cole. 
Miss  L.  M.  Brautlecht. 

In  charge  of  Buildings  and  Grounds. 
Charles  J.  Rice. 

Laboratory  Helpers. 
Hugo  Lange.  William  Pokrob. 

Sampling  Agent. 
V.  L.  Churchill,  New  Haven. 


SAN    JOSE    SCALE-INSECT. 


THE  SAN  JOSE  SCALE-INSECT;    ITS  APPEARANCE 

AND  SPREAD  IN  CONNECTICUT. 

By  W.  E.  Britton,  State  Entomologist. 

No  other  insect  has  caused  so  much  destruction  in  fruit 
orchards  throughout  the  country  as  the  San  Jose  Scale  (Aspi- 
diotus  pemiciosus  Conist.).  This  scale  was  first  noticed  by 
fruit  shippers  near  San  Jose,  Cal.,  and  was  described  by  Prof. 
J.  H.  Comstock,  in  1880.  It  was  at  that  time  doing  much  dam- 
age in  California,  and  Prof.  Comstock  regarded  it  as  the  most 
destructive  scale-insect  which  he  had  seen. 

For  several  years  the  original  habitat  of  this  insect  was  unde- 
termined, but  recent  observations  point  toward  China  as  the 
probable  country  of  its  origin.* 

Introduction  into  the  Eastern  States. 

Though  it  caused  much  damage  to  fruit  trees  in  California 
for  several  years,  the  scale  was  not  known  to  exist  in  the  Eastern 
States,  until  discovered  in  August,  1893,  at  Charlottesburg,  Va. 
In  March,  1894,  an  infested  locality  was  found  at  Riverside, 
Md.  In  both  cases,  the  introduction  of  the  insect  was  traced 
to  New  Jersey  nurseries,  which  had  received  the  scale  on  nur- 
sery stock  from  California.  Another  infested  area  was  discov- 
ered in  March,  1894,  at  De  Funiak  Springs,  Fla.  Shortly  after- 
wards Indiana,  Pennsylvania,  New  Jersey,  New  York,  Georgia, 
Ohio,  Delaware  and,  in  the  summer  of  1895,  Alabama,  Louisi- 
ana, Connecticut  and  Massachusetts  were  added  to  the  list  of 
infested  states.  At  the  present  time,  the  San  Jose  Scale  exists 
in  nearly  every  portion  of  the  United  States,  the  extreme  North- 
ern states  alone,  perhaps,  being  exempt. 

*At  a  meeting  of  the  Biological  Society  of  Washington,  D.  C,  held 
Nov.  16th,  Dr.  L.  O.  Howard  stated  "  that  he  had  received  a  letter  from  Mr. 
C.  L.  Marlatt,  announcing  the  discovery  of  the  long-sought  original  habitat 
of  the  San  Jose  scale-insect  ;  this  was  found  to  be  in  China,  in  the  region 
to  the  South  of  the  Great  Wall.  The  scale-insect  was  preyed  upon  by  a 
species  of  ladybird  beetle,  living  examples  of  which  were  now  on  their 
way  to  the  United  States." — Science,  Vol.  XIV,  No.  362,   p.   895,   Dec.   6, 

IQOI. 


4        connecticut  experiment  station,  bulletin   135. 

Discovery  and  Distribution  in  Connecticut. 

Ten  years  ago  the  San  Jose  or  pernicious  scale-insect  was 
introduced  into  Connecticut  on  nursery  stock  from  New  Jersey. 
It  escaped  notice,  however,  until  June  12th,  1895,  when  it  was 
discovered  at  New  London  by  Dr.  W.  C.  Sturgis,  Botanist  of 
this  Station.  The  insect  had  then  been  multiplying  for  four 
years  in  the  orchard  and  garden  of  Mr.  J.  L.  Raub,  and 
several  trees  had  been  killed  by  it.  A  study  of  the  locality  was 
made  and  a  bulletin  was  issued,  calling  attention  to  the  presence 
of  the  insect  in  Connecticut,  describing  its  appearance  and  inju- 
ries, and  giving  the  best  remedies  known  at  that  time.  (See 
Bulletin  No.  121,  July,  1895.) 

Soon  after,  specimens  were  received  from  Hartford  and 
Bridgeport.  During  1896,  additional  centers  of  infection  were 
found  at  Darien,  New  Haven,  Groton,  Mystic,  Farmington,  New 
Britain,  Plantsville,  and  in  the  following  year,  Meriden,  Wal- 
lingford,  Hamden,  Woodbridge  and  Greenwich  were  added  to 
the  list.  The  scale  was  found  in  Ivoryton,  Nichols,  Cheshire, 
Burnside  and  Ro  way  ton  during  1898,  and  in  several  new  locali- 
ties in  New  Haven,  Hartford  and  Bridgeport.  Previous  to  July 
1st,  1 90 1,  when  the  Insect  Pest  Law  became  operative,  the  San 
Jose  scale  had  been  found  in  seventy-eight  localities  in  this 
State.  The  names  of  the  towns  and  the  number  of  infested 
localities  in  each  town  are  as  follows : 

Ansonia — 1,  Berlin — 1,  Branford — 1,  Bridgeport — 6,  Burn- 
side — 1,  Cheshire — 1,  Cromwell — 2,  Darien — 2,  East  Haven — 1, 
Fairfield — 1,  Farmington — 1,  Greenwich — 2,  Groton — 2,  Ham- 
den— 1,  Hartford — 8,  Ivoryton — 1,  Lebanon — 1,  Lyme — 1, 
Meriden — 3,  Milford — 3,  New  Britain — 1,  New  Canaan — 1, 
New  Haven — 12,  New  London — 3,  Nichols — 1,  Norwich — 1, 
Old  Mystic — 2,  Plantsville — 1,  Rowayton — 1,  Saybrook — 1, 
South  Glastonbury — 1,  Shelton — 1,  South  Norwalk— 3,  South- 
port — 1,  Stamford — 1,  Stratford — 2,  Terry ville — 1,  Walling- 
ford — 1,  Waterbury — 1,  Woodbridge — 2. 

In  a  few  of  the  places  noted,  the  insect  was  discovered  before 
it  had  infested  more  than  one  or  two  trees.  The  immediate 
destruction  of  these  infested  trees  has  probably  wiped  out  the 
pest  from  a  very  few  localities,  but  in  most  cases  the  scale  had 
spread  to  a  serious  degree  before  it  was  discovered,  and  many 
trees  have  been  killed  and  a  still  greater  number  badly  injured 
by  its  attacks. 


san  jose  scale-insect.  5 

Nursery  Inspection  in  Connecticut. 

Inasmuch  as  this  insect  has  been  distributed  chiefly  by  means 
of  nursery  stock,  several  states  previous  to  1896  passed  laws 
requiring  that  all  nursery  stock  shipped  into  these  states  should 
be  accompanied  by  a  certificate  of  inspection  issued  by  some 
authorized  inspector.  In  the  absence  of  any  provision  for  the 
inspection  of  nursery  stock  in  this  State,  Connecticut  nursery- 
men were  debarred  from  shipping  stock  into  the  states  above 
referred  to.  During  the  season  of  1897,  the  Station  was  first 
requested  by  Connecticut  nurserymen  to  examine  their  stock 
and  grant  certificates,  if  not  found  to  be  infested.  The  Station 
complied  as  well  as  it  could  with  the  means  at  its  command,  and 
as  requests  for  inspection  grew  more  numerous,  early  in  1899 
the  Board  of  Control  formally  adopted  regulations  regarding 
such  inspection  and  the  granting  of  certificates.  A  circular 
embodying  these  regulations  was  printed  and  mailed  to  about 
seventy  nurserymen,  seedsmen  and  dealers  in  plants.  In  May, 
1899,  a  bulletin  on  Inspection  and  Care  of  Nursery  Stock, 
containing  the  Inspection  Rules,  was  published  and  distributed. 
Up  to  the  time  the  present  law  went  into  effect,  about  fifty 
inspections  had  been  made  and  thirty-nine  certificates  granted. 
While  this  arrangement  enabled  the  Connecticut  nurserymen  to 
ship  into  other  states,  it  did  not  protect  the  buyers  of  nursery 
stock  living  within  the  State.  If  a  nursery  was  badly  infested, 
so  that  a  certificate  could  not  be  granted,  the  owner  could  sell 
his  plants  and  trees  in  Connecticut,  where  a  certificate  was  not 
required.  There  was  also  nothing  to  prevent  the  shipping  of 
infested  stock  into  this  State  from  those  states  which  had  no 
nursery  inspection  laws. 

Legislation. 

The  fruit  growers  of  Connecticut,  represented  by  the  State 
Pomologieal  Society,  urged  the  passage  of  a  law  regarding  insect 
pests,  chiefly  because  of  the  damage  caused  by  the  spread  of 
the  San  Jose  scale.  The  question  was  discussed  at  the  annual 
meeting  of  the  society  in  February,  1901,  at  Hartford,  and  the 
present  law  is  the  outcome  of  this  agitation.  This  law  was 
published  in  July,  in  Bulletin  No.  134,  of  this  Station.  The 
law  provides  for  the  study  of  other  pests  as  well  as  the  San 
Jose  scale.  At  the  time  the  Connecticut  law  was  enacted,  at 
least  twenty-five  other  states  had  passed  similar  measures. 


6        connecticut  experiment  station,  bulletin  1 35. 

Life  History  of    the  San  Jose  Scale. 

Bath  the  males  and  females  pass  the  winter  in  an  immature 
state,  and  do  not  reproduce  until  the  latter  part  of  June  in  this 
latitude.  The  present  year,  young  were  first  observed  on  June 
27th.  The  female  does  not  lay  eggs,  but  brings  forth  living- 
young.  The  newly-born  scales  of  both  sexes  crawl  about  for  a 
few  hours  upon  the  twigs.  They  are  provided  with  legs,  eyes, 
antennae  and  mouth-parts.  After  they  have  found  a  suitable 
place,  they  settle  upon  the  bark,  insert  their  beaks  and  begin 
to  suck  the  juice  from  it.  Legs  and  antennae  now  disappear 
in  both  sexes,  and  the  females  lose  their  eyes.  At  first  there  is 
a  white  waxy  substance  exuded,  which  has  somewhat  the  appear- 
ance of  wool.  A  little  later  this  seems  to  melt  down  and  the 
insect  casts  its  skin.  The  skin,  together  with  the  waxy  sub- 
stance, forms  the  beginning  of  the  shell  or  covering.  After 
feeding  for  about  four  weeks,  the  insect  reaches  the  full-grown 
stage.  If  a  female,  it  then  begins  to  bring  forth  its  young, 
continuing  for  a  period  of  about  six  weeks.  The  number  of 
young  produced  by  a  single  female  varies  from  less  than  one 
hundred  in  the  early  part  of  the  season  to  nearly  six  hundred 
in  late  summer.  The  male  feeds  until  full-grown,  passes 
through  the  pupa  stage,  and  finally  the  adult  comes  forth  from 
under  the  shell,  provided  with  eyes,  wings,  legs,  antennae  and 
organs  of  reproduction,  but  with  no  mouth-parts  nor  digestive 
system.  He  can,  therefore,  eat  nothing  after  reaching  the  adult 
stage.  His  only  mission  is  to  mate  with  the  female  and  die. 
The  female,  on  the  other  hand,  after  becoming  established  upon 
the  twig,  loses  legs,  antennae,  and  eyes  never  again  to  be  pos- 
sessed of  these  organs,  while  its  mouth-parts,  digestive  system 
and  reproductive  organs  become  very  strongly  developed.  It 
cannot  therefore  move  about,  but  feeds  upon  the  juices  of  the 
plant  and  reproduces  its  kind.  There  are  three  complete  genera- 
tions each  season  in  this  latitude,  and  probably  four  in  favorable 
seasons. 

General  Appearance  of  the  Insect. 

Usually  the  insect  appears  upon  the  bark  as  a  greyish,  rough 
coating,  scarcely  noticeable  to  the  naked  eye.  At  first  there 
are  but  few  individuals,  generally  found  clustered  around  the 


SAN    JOSE    SCALE-INSECT.  7 

buds  and  at  the  branching  of  the  twigs.  Plate  III,  a,  shows  how 
the  scales  collect  in  a  groove  or  hollow  in  one  side  of  a  twig, 
as  if  they  had  sought  a  sheltered  situation.  As  the  trees  become 
more  thoroughly  infested,  the  bark  may  be  completely  covered, 
and  sometimes  there  are  several  layers  of  scales  covering  the 
bark.  In  such  cases  leaves  and  fruit  are  usually  attacked.  The 
young  scales  locate  upon  both  sides  of  the  leaf,  along  the  ribs 
(see  Plate  V,  b),  where  they  cause  a  reddish  discoloration. 
This  discoloration  also  occurs  on  fruits,  and  on  the  twigs,  especi- 
ally where  there  are  but  few  individuals,  and  it  is  apparent  not 
only  on  the  outside,  but  extends  through  the  bark  to  the  wood. 
Where  the  insect  is  found  upon  the  fruit,  it  seems  to  prefer  the 
calyx  and  the  stem  cavities.  Upon  slightly  infested  trees  the 
fruit  is  not  attacked,  but  on  trees  which  are  badly  infested  the 
fruit  is  often  so  thoroughly  covered  as  to  present  a  very  dis- 
gusting appearance.  (See  Plates  IV  and  V.)  If  we  examine 
the  insect  through  a  pocket  lens,  magnifying  perhaps  ten  diame- 
ters, we  see  that  it  is  distinctly  circular  in  outline,  somewhat 
raised  above  the  bark,  especially  in  the  center  where  there  is  a 
small  nipple,  differing  in  color  from  the  other  portion.  If 
infested  twigs  are  much  handled,  the  outer  layer  is  rubbed  away 
from  the  nipple,  leaving  it  a  bright  yellow  color.  Concentric 
circles  are  usually  apparent  between  this  nipple  and  the  outside 
edge.  The  scaly  covering  is  formed  at  the  edge  in  concentric 
layers  or  additions.  The  covering  of  the  male  is  different  in 
shape  from  that  of  the  female.  While  that  of  the  female  is 
nearly  circular  in  outline,  the  armor  of  the  full-grown  male  scale 
is  nearly  always  elongated,  with  the  nipple  near  one  end,  and 
the  lines  of  formation  are  eccentric  instead  of  concentric.  (See 
Fig.  i.) 

The  color  of  the  shell  or  covering  varies  greatly,  sometimes 
being  a  light  grey,  sometimes  being  nearly  black.  It  frequently 
turns  dark  if  the  insects  are  killed  when  half  grown.  If 
killed  when  fully  grown,  the  shells  often  assume  a  light  grey 
color,  and  finally  drop  from  the  twigs.  If  we  lift  this  shell 
or  covering  with  a  pin  or  point  of  a  knife,  we  will  see  under- 
neath a  small  yellow  object,  oval  or  circular  in  outline,  which 
appears  like  a  bit  of  yellow  jelly.  This  is  the  insect  proper  and 
is  shown  in  the  illustration  on  Plate  III,  a. 


8  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    135. 


Fig.  1.      Appearance   of    San  Jose    scale   on   peach    twig.      a.    mature 
females  :  b.  young  females  :  c.  immature  males.    About  twice  natural  size. 


Food  Plants. 

According  to  Howard*  and  Lintnerf  the  scale  occurs  on  the 
following  plants :  Apple,  pear,  quince,  peach,  plum,  cherry, 
mountain  ash,  hawthorn,  Japanese  quince,  linden,  Euonymus, 
almond,  apricot,  Spiraa,  raspberry,  rose,  cotoneaster,  gooseberry, 
currant,  flowering  currant,  persimmon,  acacia,  lilac,  elm,  osage 
orange,  English  walnut,  pecan,  weeping  willow  and  laurel-leaved 
willow. 

*  Bulletin  No.  3,  New  Series,  Division  of  Entomology,  U.  S.  Department 
of  Agriculture,  Washington,  D.  C,  p.  38. 

f  Bulletin  of  the  New  York  State  Museum,  Vol.  3,  No.  13,  p.  295. 


SAN    JOSE   SCALE-INSECT.  9 

Iii  addition  to  the  above-mentioned  food  plants,  Rolfs  and 
Quaintance*  give  chestnut,  black  walnut,  Carolina  poplar,  Lom- 
bardy  poplar,  cut-leaved  birch,  flowering  cherry,  flowering 
peach,  grape,  Catalpa,  and  sumac. 

In  Connecticut,  the  writer  has  found  it  upon  cut-leaved  white 
birch,  dogwood,  Japanese  walnut,  grape,  California  privet,  and 
several  species  of  willow.  In  Hartford  the  scale  has  already 
attacked  the  wild  choke-cherry  and  shad  bushes  in  sprout-lands. 
While  the  insect  usually  attacks  plants  belonging  to  the  Rose 
family,  there  is  reason  to  believe  that  it  may  attack  any  species 
adjacent  to  infested  trees.  Of  the  orchard  trees,  Japanese  plum, 
pear,  apple,  quince  and  peach,  are  most  often  infested,  while  the 
cherry  and  European  plum  are  less  frequently  attacked. 

The  purple-leaved  plum  is  perhaps  the  most  subject  to  attack 
of  all  the  ornamental  plants.  Mountain  ash,  hawthorn,  and 
Cydonia  are,  however,  frequently  injured  by  it. 


How  the  Scale  Spreads  from  Tree  to  Tree. 

The  young  scales  crawl  about  for  a  few  hours  on  the  bark, 
and  if  the  trees  stand  so  close  that  the  branches  interlace,  of 
course  they  can  readily  crawl  from  one  to  the  other.  They  are 
scarcely  able  to  crawl  long  distances  from  the  trunk  of  one  tree 
to  another  over  the  rough  ground,  but  are  often  blown  about 
on  fallen  leaves  and  may  reach  a  different  section  of  the  orchard 
in  that  way.  In  cultivating  nurseries,  the  workmen  brush 
against  the  young  trees,  and  it  is  quite  possible  for  some  of  the 
young  insects  to  be  carried  to  other  trees  along  the  nursery  rows. 

In  one  case,  an  orchard  became  infested  by  hitching  a  horse 
to  one  of  the  trees,  after  the  team  had  been  in  an  infested  orchard 
three  miles  distant.f  The  throwing  about  of  infested  fruit  may 
aid  in  distributing  the  pest.  Also  where  parings  of  infested 
fruit  are  thrown  out  into  gardens,  there  is  danger  that  near-by 
trees  may  become  infested. 

"As  a  rule,  however,  the  insect  is  carried  to  distant  trees  either 
by  other  insects  or  upon  the  feet  of  birds. 

*  Coccidse  Americanae,  Decades  I  and  II,  No.   15. 

f  Bulletin  No.  3,  New  Series,  Division  of  Entomology,  U.  S.  Department 
of  Agriculture,  Washington,  D.  C,  p.  50. 


io      connecticut  experiment  station,  bulletin  1 35. 

Effect  upon  Trees. 

The  effect  on  the  vitality  of  the  tree  is  not  apparent  until  the 
twigs  become  nearly  covered  by  the  insect.  Then  it  may  be 
noticed  that  the  tree  seems  unthrifty,  but  the  scale  is  so  incon- 
spicuous that  frequently  the  tree  loses  some  of  its  branches  or 
dies  before  the  cause  of  the  trouble  is  discovered.  The  illus- 
tration on  Plate  II  shows  a  peach  tree  which  has  been  severely 
injured,  and  the  branches  are  dead,  but  the  trunk  is  still  alive 
and  making  an  effort  to  grow  a  new  top.  This  form  of  injury 
is  one  often  seen,  and  frequently  the  owner  does  not  discover 
the  cause  until  his  trees  reach  this  condition.  A  plum  tree 
killed  by  the  scale  is  shown  on  Plate  I.  The  length  of  time 
required  to  kill  a  tree  depends  on  various  factors.  In  certain 
seasons  the  species  multiplies  much  more  rapidly  than  in  others, 
depending  undoubtedly  upon  the  weather  and  the  abundance  of 
natural  enemies.  The  writer  has  known  of  several  localities 
where  ornamental  plants  were  attacked  and  no  measures  taken 
to  destroy  the  scale,  yet  for  two  or  three  years  the  insect  has 
not  spread  to  any  appreciable  extent.  On  the  other  hand,  in  cer- 
tain orchards,  it  has  spread  with  great  rapidity  in  spite  of  vigor- 
ous combative  measures.  In  Mr.  Raub's  garden  at  New  Lon- 
don, large  peach  trees  were  killed  by  the  scale  in  four  years. 

Remedies. 

All  infested  trees  which  are  worthless  or  of  little  value  should 
be  destroyed,  as  the  owner  cannot  afford  to  treat  them ;  he 
had  better  obtain  new  trees. 

Spraying. 

There  have  been  many  different  applications  used  in  Connecti- 
cut to  kill  this  scale-insect.  The  most  successful,  perhaps,  is 
either  crude  oil,  applied  just  before  the  leaves  are  put  out  in  the 
Spring,  or  a  mixture  of  kerosene  and  water  (20  to  25  per  cent, 
kerosene),  applied  at  the  same  time.  The  crude  oil  possesses 
one  advantage.  A  portion  of  it  stays  on  the  bark  for  several 
months,  so  that  it  would  seem  impossible  for  the  young  scales 
to  become  established.  Kerosene,  on  the  other  hand,  evaporates 
readily  and,  after  a  few  weeks,  can  not  be  detected  by  odor  or 
by  the  appearance  of  the  twigs.     Experiments  conducted  by  us 


SAN    JOSE    SCALE-INSECT.  II 

during  the  past  season,  show  that  either  the  crude  oil,  or  20  per 
cent,  kerosene  and  water,  if  thoroughly  applied,  will  kill  the 
insects  without  causing  any  serious  injury  to  the  trees.  An 
account  of  these  experiments  will  appear  in  a  forthcoming 
Bulletin.  It  is  not  safe  to  apply  any  form  of  petroleum  on  a 
damp,  cloudy  day.  It  must  be  used  in  pleasant  weather,  and 
must  be  applied  in  the  form  of  a  fine  spray. 

We  have  found  the  "Kerowater"  barrel  pump,  made  by  the 
Goulds  M'f'g  Co.,  Seneca  Falls,  N.  Y.,  to  give  satisfaction  in 
orchard  work.  For  a  few  small  trees  in  the  garden  there  is 
probably  nothing  better  than  the  "Success"  bucket  pump  made 
by  the  Deming  Co.,  Salem,  Ohio.  These  pumps  are  not  kept 
in  stock  by  local  dealers,  but  must  be  ordered  from  the  manu- 
facturers. The  "Vermorel"  is  the  best  nozzle  we  have 
employed  for  kerosene  spraying,  but  a  cap  with  small  aperture 
should  be  used.  In  infested  orchards  this  spraying  is  likely  to 
be  adopted  as  the  best  practical  way  of  holding  the  pest  in  check. 
Fumigating  is  here  too  expensive. 

According  to  experiments  made  in  New  Jersey,  certain  grades 
of  crude  oil  are  liable  to  cause  injury  to  the  trees.  If  the  oil 
has  a  specific  gravity  of  not  less  than  430  (Beaume),  there  is 
little  danger.  It  need  not  be  above  45  °  however.  As  the  term 
''crude  petroleum"  is  rather  vague  in  meaning,  it  is  necessary  to 
specify,  in  ordering,  what  grade  of  oil  is  required.  In  order 
that  Connecticut  fruit  growers  may  obtain  the  proper  grade 
of  oil  for  insecticide  purposes,  I  have  arranged  with  the  Standard 
Oil  Company  to  furnish  it.  Orders  should  be  sent  to  the  Provi- 
dence Department  of  the  Company,  Mr.  P.  M.  Watt,  Manager, 
136  South  Water  St.,  Providence,  R.  I.  This  oil  is  not  kept  in 
stock  at  the  distributing  stations,  but  shipments  can  be  made 
quickly  from  New  York.  The  present  price  is  9^  cents  per 
gallon,  including  barrel,  but  of  course  the  price  is  subject  to 
changes.     In  ordering,  call  for  "Insecticide  Oil." 

A  solution  of  whale-oil  soap  (2  lbs.  of  soap  to  1  gallon  of 
water)  sprayed  upon  the  trees  is  regarded  as  the  best 
remedy  in  many  localities.  It  is  probably  less  liable  to  injure 
trees  than  the  kerosene  or  crude  oil,  and  may  be  applied  at  any 
time  during  the  winter.  But  it  is  an  expensive  treatment  for 
large  orchards,  and  from  our  observations  in  Connecticut  it 
does  not  seem  to  .be  as  effective  in  destroying  the  insects  as 


12         CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    I35. 

kerosene  or  crude  oil.  It  is  also  difficult  to  apply  in  the  form 
of  a  spray.  Whale-oil  soap  fairly  uniform  in  composition  may 
be  obtained  from  the  manufacturers,  James  Good,  514-518  Hurst 
St.,  Philadelphia,  Pa.,  and  Leggett  &  Bro.,  301  Pearl  St.,  New 
Ybrk. 

The  above-mentioned  treatment  applies  only  to  dormant  trees. 
If  the  insect  is  discovered  during  the  Summer  when  the  trees 
are  not  dormant,  it  may  be  held  in  check  for  the  season  by 
spraying  with  1 5  per  cent,  kerosene  and  water,  or  whale-oil  soap 
solution  (1  lb.  to  5  gallons  of  water),  which  will  kill  most  of 
the  young  scales  which  are  crawling  upon  the  bark. 

Fumigating. 

In  nurseries  where  the  trees  are  dug  up  in  shipping  season, 

the  scales  upon  them  can  easily  be  destroyed  by  fumigating  with 

hydrocyanic  acid  gas.     A  tight  box,  tent,  or  room,  is  required 

for  this  purpose,  and  our  leading  nurserymen  are  now  provided 

with  some  sort  of  equipment  for  fumigating  their  nursery  stock. 

In  fact,  some  of  their  large  orders  reach  them  with  the  request 

that  the  stock  be  fumigated  before  being  sent  out:   even  when 

it  is  not  known  to  be  infected.     The  formula  which  we  have 

been  using  in  Connecticut  requires  for  each  100  cubic  feet  of 

space, 

Cyanide  of  potash  (97  per  cent.) 25  grams,  %  oz.  (by  weight) 

Sulphuric  acid  (Sp.  G.   1.83) iA/i  oz.  (liquid  measure) 

Water 1%  oz.  (liquid  measure) 

The  enclosed  space  should  be  computed  with  care,  and  the  chemi- 
cals measured  out  accordingly.  The  house  should  of  course 
be  filled  with  the  trees  before  preparing  the  chemicals.  A  stone- 
ware jar  of  suitable  size  makes  a  good  generator.  The  water 
should  first  be  put  into  this  jar  and  the  acid  poured  in  slowly 
with  constant  stirring.  The  jar  should  be  set  inside,  and  within 
easy  reach  of  the  door  or  cover.  The  cyanide  is  then  dropped 
into  the  jar  quickly,  and  the  house  closed  from  the  outside. 
The  person  should  leave  at  once,  as  the  fumes  are  extremely  pois- 
onous and  might  cause  death  if  one  should  breathe  them.  The 
trees  should  be  left  for  half  an  hour,  when  the  house  may  be 
opened  in  order  to  let  the  fumes  escape.  It  is  not  safe  for 
persons  to  enter  for  several  minutes.  While  this  treatment  is 
not  certain  to  kill  every  individual  scale-insect,  it  is  one  of  the 


SAN    JOSE    SCALE-INSECT.  1 3 

surest  methods  that  we  know  of  destroying  them.  Small 
orchard  trees  can  be  fumigated  in  this  manner,  by  covering  them 
with  a  gas-tight  tent,  beneath  which  the  gas  is  generated,  but 
for  large  orchard  trees,  an  expensive  outfit  is  required  to  handle 
the  tents.  There  is  also  some  difficulty  in  computing  the  space. 
Chiefly  on  account  of  the  expense,  however,  this  has  not  been 
practiced  to  any  extent  in  Connecticut.  The  fumigation  of 
nursery  stock  must  be,  from  now  on,  a  common  practice.  The 
materials  may  be  obtained  from  any  wholesale  druggist. 

Summary. 

( i )  The  San  Jose  Scale  appeared  and  caused  much  destruc- 
tion of  fruit  trees  in  California  twenty  years  ago.  China  is 
probably  the  country  of  its  origin. 

(2)  It  was  first  found  in  the  Eastern  states  in  1893,  and 
now  occurs  in  nearly  all  the  states  of  the  Union,  except  perhaps, 
the  extreme  Northern  ones. 

(3)  The  scale  was  brought  into  Connecticut  on  nursery 
stock  ten  years  ago,  but  not  discovered  until  1895.  Seventy- 
eight  infested  localities  had  been  found  up  to  July  1st,  190 1, 
when  the  new  Insect  Pest  Law  went  into  effect. 

(4)  The  Station  began  the  work  of  inspecting  nurseries  in 
1897,  at  the  request  of  nurserymen.  This  enabled  them  to  ship 
stock  into  other  states  where  inspection  laws  existed.  Fifty 
inspections  were  made  and  thirty-nine  certificates  granted  under 
this  arrangement.  Twenty-five  other  states  had  enacted  inspec- 
tion laws,  before  the  Connecticut  law  was  passed. 

(5)  The  full  grown  female  scale  gives  birth  to  living  young, 
which  crawl  about  for  a  short  time  and  then  settle  upon  the 
bark.  There  are  three  or  four  generations  each  season.  They 
feed  by  sucking  the  juices  from  the  tree.  Each  female  may 
produce  from  less  than  one  hundred  to<  six  hundred  young. 

(6)  The  scale  is  inconspicuous  and  is  seldom  noticed  until 
the  vitality  of  the  tree  is  impaired,  at  which  time  the  bark  is 
usually  coated  with  a  roughish  grey  substance.  The  reddish 
discoloration  may  be  found  around  each  individual.  Leaves 
and  fruit  are  also  attacked.  The  female  scale  is  nearly  circular 
in  outline,  while  the  male  is  somewhat  elongated.  If  the  scale 
is  lifted,  the  insect  proper  may  be  seen  underneath,  by  the  aid  of 
a  lens,  as  a  yellow  object. 


14         CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    I35. 

(7)  Common  fruit  trees  and  plants  of  the  Rose  family  are 
usually  preferred  by  the  insect,  but  it  is  liable  to  attack  almost 
any  variety  of  tree  or  plant  that  may  be  growing  near  infested 
trees. 

(8)  Though  the  young  scales  crawl  short  distances,  they  are 
usually  carried  from  one  tree  to  another  by  other  insects,  or 
upon  the  feet  of  birds.  They  may  also  be  carried  upon  fallen 
leaves,  fruit,  or  the  clothing  of  persons,  etc. 

(9)  The  vitality  of  the  tree  is  gradually  lessened  by  the  hordes 
of  insects  sucking  its  sap.  The  pest  is  seldom  noticed  until 
some  of  the  twigs  die.  Entire  trees  have  been  killed  in  four 
years  in  Connecticut  by  the  scale. 

(10)  Spraying  the  trees  just  before  leaves  appear  in  the 
Spring,  with  crude  oil,  or  with  a  mechanical  mixture  of  kero- 
sene oil  and  water,  using  20  per  cent,  kerosene,  is  the  best 
remedy  that  we  can  now  recommend  for  large  orchard  trees. 

Whale-oil  soap  and  water,  in  the  proportion  of  2  lbs.  of  soap 
to  1  gallon  of  water,  sprayed  upon  the  dormant  trees,  is  also  an 
effective  treatment.  Growing  trees  may  be  treated  with  15  per 
cent,  kerosene  and  water,  or  whale-oil  soap  ( 1  lb.  in  5  gallons  of 
water).  For  nursery  stock,  fumigating  with  hydrocyanic  acid 
gas  is  the  cheapest  and  most  effective  treatment. 


PLATE    I 


\ 


«^^k    'i 


« 


Plum  Tree  killed  by  the  San  Jose  Scale-Insect. 


PLATE   II 


Peach  Tree  severely  injured  by  the  San  Jose  Scale-Insect. 


PLATE    III 


(a)  Infested  Peach  Twigs.  Mature  females  and  young  scales  clustered 
in  a  groove  of  the  twig  may  be  seen  at  the  left.  A  female  with  the 
shell  or  covering  raised  is  shown  at  the  right.     Considerably  enlarged. 


:K 


■         .:™    ■:■■■■         '    ■■    K* 


{b)  Plum  Twigs  nearly  coated  over  by  San  Jose  Scale.     Natural  size. 
Appearance  of  Infested  Twigs. 


PLATE    IV 


(a)  Pears  badly  infested. 


(b)  Infested  Apples  showing  the  discoloration  around  the  Insects. 
Appearance  of  Infested  Fruit. 


PLATE   V 


(a)  Plums  showing  the  reddish  discoloration  caused  by  the  Insects. 


(b)  Leaves,  showing  the  tendency  of  the  Insects  to  locate  near  the  veins. 
Infested  Leaves  and  Fruit  of  Japanese  Plum. 


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